1. Technical Field
The present invention relates to a rotational hydraulic transformer capable of continuous increasing/decreasing of pressure, to be suitably used for driving concrete crushers and the like.
2. Background Art
Known arrangements for crushing concrete generally use hydraulic-driven crushers and the like which are capable of exhibiting great force. Accordingly, due to the fact that force stronger than normal is necessary for breaking steel reinforcements within the concrete when crushing steel-reinforced concrete buildings and the like, temporary increase in output is conducted by means of increasing hydraulic pressure when necessary. This is in order to maintain the system pressure low at normal times, to reduce loss of force and to improve durability of hydraulic equipment. Accordingly, such types of hydraulic equipment is provided with hydraulic mechanisms for raising the system pressure above the predetermined system pressure for supplying to an actuator. There are generally known the two following types of pressure raising methods used in such hydraulic mechanisms for raising pressure.
(A) Equipment known as a booster (intensifier) cylinder device, wherein cylinders having different effective areas ahead of and behind pistons fitted into the cylinders are used, so as to raise the hydraulic pressure connected to the side with smaller effective area than the hydraulic pressure connected to the side with greater effective area. PA1 (B) Arrangements wherein an input shaft of a hydraulic pump and an output shaft of a hydraulic motor are mechanically linked, in which the hydraulic pressure obtained from the pump is raised above the hydraulic pressure driving the motor, by means of making the volume of the motor to be greater than the volume of the pump. PA1 a first volume increasing/decreasing mechanism for cyclically and continuously increasing/decreasing the volume of a plurality of first annularly arranged spaces by shifting the phase of each, by employing relative positional change of two relative moving members; PA1 a second volume increasing/decreasing mechanism for cyclically and continuously increasing/decreasing the volume of a plurality of second annularly arranged spaces by shifting the phase of each, wherein the second volume increasing/decreasing mechanism shares the two relative moving members in common, and cyclically and continuously increasing/decreasing the volume of the second spaces by employing relative positional change of the two relative moving members; PA1 a pair of first channels, wherein one of the first channels is connected to the first spaces of which the volume is increasing while the other first channel is connected to the first spaces of which the volume is decreasing; and PA1 a pair of second channels, wherein one of the second channels is connected to the second spaces of which the volume is increasing while the other second channel is connected to the second spaces of which the volume is decreasing; PA1 wherein an increasing/decreasing volume of the first spaces and an increasing/decreasing volume of the second spaces in one cycle are made to be different.
Particularly, regarding concrete crushers, booster cylinder devices based on the method described in (A) are often used to raise pressure, and examples of such include that disclosed in Japanese Unexamined Patent Publication No. 62-297508, described below in detail.
However, booster cylinder devices such as described in (A) have the problem that they are basically not suitable for continuous operation. This is because the operation of increasing pressure ends at the point that the piston reaches one of the stroke ends. In order to solve this problem, the booster cylinder device described in the aforementioned Japanese Unexamined Patent Publication No. 62-297508 has generally the following construction. Making description with reference to FIG. 11, booster chambers 02, formed to the right and left sides in FIG. 11 of a booster piston 01 for raising pressure having a large-diameter portion 011 partway thereupon, are connected via check valves provided to the outside of each of the booster chambers 02, a high pressure port OP and low pressure port OT are each connected to booster piston chambers 03 formed to the front and rear of the large-diameter portion 011 so as to be switchable by a switching valve 04, and three concave grooves 051, 052, and 053 provided to the inside face of the small radial portion of a cylinder 05 are arranged such that the groove 051 on one end is connected to high pressure P1 while the groove 053 on the other end is connected to low pressure T, and the middle groove 052 is connected to a control port 041 for the aforementioned switching valve 04, and a concave groove 012 is provided to the outside face of the small diameter portion of the booster piston 01 so as to connect the middle groove 052 to either one of the groove 051 on one end or the groove 053 on the other end, at the time that the booster piston reaches the proximity of one of the stroke ends. Incidentally, the terms "right" and "left" in the subsequent description here shall refer to that in FIG. 11.
In FIG. 11, a state is shown wherein the high pressure port 0P is connected to the right booster piston chamber 03 and the booster piston 01 is moving toward the left. Subsequently, at the point that the booster piston 01 reaches the proximity of the left stroke end, the middle groove 052 is connected to the groove 051 on one end, and high pressure is introduced to the switching valve control port 041. The switching valve 04 then moves to the right, such that the high pressure port OP is connected to the left booster piston chamber 03 and the low pressure port OT is connected to the right booster piston chamber 03 in the Figure, thereby the high-pressure fluid and low-pressure fluid each introduced to the right and left booster piston chambers 03 are inverted. As a result, the booster piston 01 reverses direction before reaching the stroke end and starts moving in the direction 0B. Also, the reverse operation is performed at the point that the booster piston 01 reaches the proximity of the right stroke end, and consequently, the booster piston 01 performs reciprocating motion. In other words, the pressure in the right booster chamber 02 is raised while the booster piston 01 is moving in the right direction, and the pressure in the left booster chamber 02 is raised while the booster piston 01 is moving in the left direction, so that one of the booster chambers 02 is connected with the booster port P2 via the check valve, meaning that boosting is performed unceasingly.
However, this construction has the following shortcomings. Firstly, the pressure of the booster port P2 always greatly drops at the time of reversing the direction of the booster piston 01. This is basically owing to the reciprocating motion of the piston, and this is an unavoidable phenomenon with this construction. Specifically, considering the aforementioned direction reverse of the booster piston 01, the pressure of one of the booster chambers 02, which had been subjected to raising, begins to be rapidly decompressed at the time of the direstion reverse, but the other booster chamber 02 does not immediately begin to be pressurized due to the elasticity of the fluid and the momentum of the piston 03, resulting in decrease of hydrauric pressure of the booster port P2 which should be raised.
Secondly, besides the cylinder device itself as a main body, auxiliary machines such as the switching valve 04 and many parts for piping are necessary.
Thirdly, in the event that the booster piston 01 is made to be too small, the momentum of the piston is so reduced to the extent that the booster piston 01 may stall at the time of switching. One reason thereof is that a throttle is created between the grooves 051, 052, or 053 and the concave groove 012 since the booster piston 01 moves with the slightest force, such that high pressure or low pressure is not completely connected to the control port 041, and the booster piston 01 stops at the pressure value which holds the switching valve at an intermediate position at which the force from the port booster chamber 02 and the booster piston chamber 03 are balanced. Accordingly, it is difficult to make the piston to be compact.
Next, regarding the method (B), linking two hydraulic mechanisms, namely, a pump and motor, causes difficulty in reducing the size, and the number of parts and the cost both increase. Further, piping for linking becomes necessary, complicating assembly.
In order to solve the above problems, the rotational hydraulic transformer according to the present invention relates to a hydraulic mechanism which avoids the above-described problems which are inherent to linear cylinder devices. The hydraulic mechanism of the present invention utilizes rotation but is entirely different from the conventional concept of linking two hydraulic mechanisms, namely, a pump and motor, but rather uses the differences in increasing and decreasing volume between a plurality of first annularly arranged spaces and a plurality of second annularly arranged spaces in order to completely eliminate or greatly reduce pulsation, thereby realizing continuous boosting and also reducing in size and weight.